Early detection of potential health threats is crucial for taking actions in
time. It is unclear in which information source an event is reported first and,
information from various sources can be complementing. Thus, it is important to
search for information in a very broad range of sources. Furthermore, real-time
processing is necessary to deal with the huge amounts of incoming data in time.
Event-driven architectures are designed to address such challenges. This will be
shown in this paper by presenting the architecture of a public health surveillance
system that follows this style. Starting from concrete user requirements and
scenarios, we introduce the architecture with its components for content collection,
data analysis and integration. The system will allow for the monitoring of events in
real-time as well as retrospectively.